    //将base64转换为blob
   let dataURLtoBlob = function(dataurl) { 
        var arr = dataurl.split(','),
            mime = arr[0].match(/:(.*?);/)[1],
            bstr = atob(arr[1]),
            n = bstr.length,
            u8arr = new Uint8Array(n);
        while (n--) {
            u8arr[n] = bstr.charCodeAt(n);
        }
        return new Blob([u8arr], { type: mime });
    }
    //将blob转换为file
    let blobToFile=function(theBlob, fileName){
       theBlob.lastModifiedDate = new Date();
       theBlob.name = fileName;
       return theBlob;
    }

export {
    dataURLtoBlob,blobToFile
}